A fix for San Francisco's sinking skyscraper could cost upwards of $100 million, and no one wants to foot the bill

A view of Millennium Tower in San Francisco. Eric Risberg/AP There may be a fix in the works for San Francisco's very own "leaning tower."

Millennium Tower has sunk 17 inches and tilted 14 inches since its completion in 2008. Satellite images suggest the residential high-rise — home to more than 200 multimillion-dollar condos — will continue to sink two inches per year.

A pair of engineering firms hired by developer Millennium Partners and other parties said they have a solution to stabilize the tower and "prop it back upright."

The LERA firm and DeSimone Consulting Engineers want to drill 50 to 100 new piles (a type of foundation in the shape of a pillar) 200 feet down to bedrock from the building's basement, according to the Chronicle. These piles would support the existing 900 piles in the ground.

"Our top priority has always been getting a 'fix,'" PJ Johnston, a spokesperson for 301 Mission St. Development — a business arm of Millennium Partners — told Business Insider.

Johnston declined to comment on progress that's been made to install the new piles, citing a confidentiality agreement as part of an active mediation between Millennium Partners, the homeowners association, and other parties, to address the building's problems.

The engineering teams told the Chronicle the fix will cost between $100 million and $150 million, which is considerably less than what some experts expected.

No one wants to foot the bill for the repair, largely because the tower's developers, residents, and neighbors can't agree on who is at fault for Millennium Tower's sinking.

Millennium Partners blames nearby construction at the Transbay Transit Center. The group argues that construction for the bus terminal pumped too much water out of the ground, causing sand to compress and the building to settle through a process called dewatering.

"We have long warned that construction at these adjacent sites — including ongoing dewatering — was causing vertical and differential settlement of the building. These impacts are continuing," Johnston told Business Insider. "We will support any effort by the [homeowners association] to hold accountable those parties that have caused these impacts on the building."

The Chronicle said there will likely be negotiation and possible litigation, involving Millennium Partners, the homeowners association, and TJPA, to decide who's picking up the bill.

"We are confident that this mediation will be able to resolve the building issues, including any concerns about settlement and tilt, so long as the [homeowners association] remains committed — as are we committed — to the success of the mediation process," Johnston said.